Keep on truckin'

For your pleasure, here are some pictures of the truck, as it progresses.

Click on the pictures to see a much larger version.
Green is the final paint color for the truck. The ends were painted green early, so as to allow pieces of the truck to be bolted up.

A previous post talked about the connecting air hoses and brackets. Significant work has gone into refurbishing those parts.

In most cases, the work needed is merely surface prep and paint. Last Saturday, the beadblast cabinet was in use continuously with people waiting for time on it.

In this particular case, three air pipes require three valves on each end, for six total. Every one needs "lapping". The valve is first pipe-plugged, then beadblasted with great care to keep beads out of the innards of the valve. Then the valve is disassembled and cleaned. Often, there are scratches on the surface of the valve, which will cause leaks.

The heart of the valve is this cone-shaped piece, which fits into a valve body of same proportions (below). Ignore the rod at the top, that's an improvised handle to make this job easier.

The cone is coated with lapping compound, which is an abrasive compound made into a slurry. Liquid sandpaper. The cone is then fitted into the valve body, rotated back and forth several times about 1/4 turn, lifted out, seated in a different place and rotated again. This constant reseating is necessary to avoid adding new scratches. Periodically the valve must be lifted out, washed off in solvent, and inspected. You only want to remove barely enough material to remove scratches. Finished, it looks like this.

Many other parts needed surface prep and painting. The primer used is Awlgrip 545 primer. This is a 2-part epoxy primer comparable to some of the best automotive finishes. Because it's designed for boats, it's designed to be brushed as well as sprayed. That's useful, because the safety precautions in spraying it are considerable, but with brushing it's mainly a matter of "don't get it on your skin". All the same can be said about Awlgrip Topcoat, the finish coat used on these parts.

The paint room was kept busy.

A peek at the truck

Repairing the wreck damage on one end of SN 1005 required removing that truck. Because of the considerable air, electrical, frame and coupler work required, the truck has been stored outside (under tarp) until recently. Now with that work complete, it is time to prepare the truck for service.

Here it is, brought into the shop, and behind it is a real treat - freshly painted Muni 1016!

Note the third rail pickup assembly has been removed from this side.

Birney 62 is not in the shop for repair. The shop is a temporary carbarn while a culvert is dug under the yard of Carbarn 1. The culvert will correct a drainage problem and allow restoration of the duck pond.

Draft gear, redux

The draft gear and couplers are a big job, and the work continues. Here, you see the coupler mated with its draft gear housing. The entire draft housing has been freshly painted with Awlgrip. You can see the hole on the right where it ties to the carbody and pivots. What you can't see is the draft gear including its essential spring, but it's a fairly conventional Janney arrangement. More on that later.


Here is the other, less freshly painted, draft gear mounted on the car - my apologies for the picture quality but it was very low-light. You can get a peek, through the side hole, of the outer draft gear spring - there's a second spring nested inside the first.

There are several interesting features in this shot. First, to the lower right, is a 3-way pivot arm directly on the coupler pivot point. It has three arms, which connect the cut levers on each side to the coupler itself. One of the cut levers was forged at a blacksmith (see previous post).

And on the upper left, you see a bracket. This is one of several brackets along the coupler. They carry three air pipes, and one heavy 600V jumper cable. Normally, connections like this come from the carbody. But on 1005, the connections are hung from the coupler shank itself, so they pivot as the car pivots. That means it won't part an air hose going around a sharp curve.

Here you see the brackets which ride closer to the coupler. This is where three air pipes connect to the air hoses and "glad hands". An electrical connection is made here as well; this carries third rail current down the train. Another connection, up high, trainlines trolley power.

The three air hoses are not the same as a locomotive. The first connection is, as you would expect, brake pipe. The second connection is a signal whistle, which allows the conductor to signal the motorman. The third connection is not main reservoir. It is called "control pipe", and it provides the air supply to the brake stand on a control trailer. In this configuration, the brake stand does not have a feed (reducing) valve - "control pipe" contains reduced pressure at the nominal brake pipe pressure.

Now, let's revisit the draft gear itself. Earlier this year, there was an RyPN discussion about couplers and draft gear on a narrow gauge car at the SPCRR, Society for Preservation of Carter Railroad, in Ardenwood, Fremont, CA.

Here's one of the narrow gauge couplers Randy was referring to. It's now the Sunday before Labor Day, and the coupler and draft gear is ready to reinstall in the NWP caboose. Here you see draft gear that is very similar to SN 1005's. In draft (pulling), the forces pull around the C-strap, compress the spring, which pushes against the left "ears" which press against the car. In buff (pushing), the forces push directly down the coupler and compress the spring, which pushes the right "ears". This entire assembly can be lifted by two men, rather unlike SN 1005's. The wooden blocks, I'm told, compensate for the draft gear having been converted from link-and-pin to knuckle many years ago.

Welding a cut lever - the old fashioned way

To uncouple, you pull a cut lever. SN 1005 has four cut levers - one on each corner of the car. These connect through a link rod to the couplers themselves. They are made of about 1/4" steel rod.

Three of the cut levers were intact, and could be reused. The other one had been lost or destroyed, and had been replaced by an improvised cut lever which was functional, but not historically appropriate.

The original cut levers had been forge welded by a blacksmith. Fortunately, a blacksmith capable of the job operated at the Ardenwood farm in Fremont, California, and frequently did projects for the SPCRR, also at Ardenwood. Dave Johnston took the materials there. Here is a photo of the blacksmith shop.

And here is a photo of the crew at work (not on our cut lever)...

Riveting draft gear

SN 1005's excursion career saw it shipped all over northern California in freight trains. It is not built as strongly as freight cars, so it tended to take the brunt of the damage in rough handling and switching accidents. Needless to say, a lot of this fell on the couplers and draft gear. Previously, both ends' couplers and draft gear had been disassembled. Subassemblies had been repaired, including a complex steel forging in the shape of a "C" which wraps around the draft gear springs. This is riveted to the coupler body with two large 1-1/4" rivets.

These rivets are special. They are flat-head rivets. They must lay flush against the draft gear when they are done. Their holes are countersunk with a bevel, so the rivet is shaped like a flat-head screw. It's that way on both sides.

What makes a rivet a rivet (and not a bolt) is that it is heated to yellow-hot, inserted into the hole, and hammered. This makes the rivet expand fully into the hole, leaving no space. If the hole is irregular, the rivet fills it all, at least near the hammered end. Most rivets start with their familiar button-head already on one end. But this rivet is flat-head. It must expand into a countersunk hole. To get a good start, the rivet is turned with the correct shape of head. Even so, this will be heated, and will deform and expand to fill the hole.

One of the tricks with any riveting job, and this one especially, is to compute the correct amount of metal to be in the rivet to expand into the hole and yet leave the correct amount of metal in the head. With button head rivets there are familiar formulas. Ah, but what volume of metal will fill that beveled countersink? That required the sharp pencil and a fair bit of calculating.

Another way to make the rivet fit is to drill out the hole. This was more complicated because the coupler body is hollow, so each hole through the coupler body is not continuous steel. When the hole picks up on the other side, it doesn't quite align. "Misaligned holes" is a common problem when riveting. (Especially when riveting bridges, hold that thought.) We started with drill bits, stepping up in 1/64" increments, which made the developing hole tend to center itself. The coup de grace was delivered by a bridge reamer. It has a tapered shank, which centers on a slightly misaligned hole, and aligns it by enlarging it. Our finishing size was 1 and 5/32", or 1/32" over nominal rivet size.

Another problem - how do you hold the rivet gun onto a flat-head rivet? On a normal button-head rivet, the rivet itself does the job. The shop crew created a solution: The C-shaped bar was steel, so it could be welded. They found a pipe that would just fit around the rivet gun. They cut about a 2-inch length of that pipe, and tack welded it in the right place to guide the rivet gun over the rivet. Problem solved!

On the first coupler, this preparatory work was done Tuesday. On Wednesday, the rivets were driven. The rivet must easily go into the hole when it is heated. Heating makes it bigger. Which is the idea behind drilling the hole 1/32" oversize. It wasn't enough - on our first try, the hot rivet would not go in the hole. It was let to cool, and 1/32" was turned off it on the lathe. It worked the second time. Lessons learned, the second rivet went in fine. A fair bit of grinding followed, and riveting is now complete on one coupler. You can barely tell there are rivets there.

Are the rivets in shear? No, they aren't. Coupler draft (tension) and buff (compression) both go through a big spring that goes in the empty space you see. More on that later.

Reverser repaired

Over the previous week, the 1005's reverser drum was repaired, tested and reinstalled. The reverser's job is to reverse field connections on each of the traction motors. On a series-wound traction motor, the field is in series with the armature. That means every field must take full traction motor current, and thus, so must the reverser. It must have a circuit for each motor, i.e. four, and at least four contact blades per circuit.

This makes for a very big switch, and it's built as a multi-pole drum switch. Because of its size, it takes a lot of force to throw. The muscle actually comes from air. Electrical signals operate a "magnet valve" which applies air to a piston, which throws the drum switch over. There are two magnet valves, one for each direction. The electrical signal to each magnet valve goes through an interlock on the drum itself, which cuts power to the magnet valve (and thus air to the piston) once the drum reaches the desired position.

You may recall two articles (1) (2, photos) about the third rail changeover switch. This switches even more current, but only one circuit. They were usually reversers with their many contacts ganged together to increase current capacity.

The Westinghouse HL equipment also has switch groups, which is a footlocker-sized cabinet with 6-8 large contactors in it. 1005 in fact has two complete sets of switch groups; that's because the additional complexity of the 600/1500V changeover required more switches than one group contained. Al has been overhauling some of the switch groups. Here you see him working on some interlock fingers. These don't carry full traction current, but signaling current. Their job is to interlock other contactors which should never be closed at the same time, such as series/parallel transitions.